As government damage assessors combed north Minneapolis for evidence of whether Sunday's tornado qualifies the city for federal disaster relief, new numbers suggest that damage to public facilities already may have met the threshold.

City Engineer Steve Kotke said a rough estimate is that public facilities sustained $10.3 million in damage, ranging from hundreds of tangled traffic signs, to lost park structures to 150 punctured tires on city vehicles from running over debris in the streets.

The federal threshold is $6.4 million in uninsured damage to public property. Meanwhile, officials said they've now declared 147 properties unfit for occupancy because of structural problems.

Some 274 buildings suffered major damage, meaning walls or roofs were destroyed. Another 1,608 had minor damage, meaning a property can be made habitable quickly. Still another 1,831 had minimal damage that allows people to stay without repairs.

Those classifications are used by the Federal Emergency Management Agency (FEMA), which is using joint federal-state teams to determine an official damage estimate that could trigger a presidential disaster finding. They hoped to have the estimate by the weekend.

If President Obama declares a federal emergency, it would open avenues for federal aid to help people, nonprofit agencies, businesses and local governments rebuild.

Kotke told the City Council on Thursday that the city has relaxed regulations to make cleanup easier for residents. It opened the North Side's waste depot to construction debris, saving residents a trip across the city. They'll be able to dump up to 10 loads rather than the usual annual limit of six.

The city is beginning to remove toppled boulevard trees that fell onto private property. Although it doesn't usually do so, it will haul away tree limbs dragged to the boulevard. Kotke said he expected all alleys to be clear by the end of Thursday and said garbage trucks will return to serve households where alleys were blocked this week.

More than 1,700 truckloads of fallen trees have been hauled to the Park Board-owned former Scherer Bros. Lumber yard in northeast Minneapolis for chipping.

City crews have been pulling 12-hour shifts. They'll take a two-day break after a planned mass volunteer cleanup on Saturday, for which details still are being determined, and then return to long shifts Tuesday.

Between 400 and 800 volunteers already are assisting residents with clearing debris, according to Noah Schuchman, a liaison to the Council for regulatory and emergency issues. He said the number of people at the armory shelter in northeast Minneapolis was down to 40 Wednesday night, compared to 257 on Sunday.

The biggest concentrated city loss may be at the water treatment plant in Fridley, where Kotke put damage at $1.5 million. But that didn't affect water production. The storm felled mature oaks, damaged sheds and punctured roofs there, he said.

'Here until we finish'

Stepping over fallen power lines and broken trees while chain saws shrieked on every block, visiting federal evaluators spent a few minutes at each house they surveyed Thursday morning.

"We'll be out here until we finish," said Scott Richardson of FEMA. He said the damage looked like a "typical tornado."

"One place gets hit hard. Next door, there's not much," he said.

As the group surveyed a stretch between West Broadway and Golden Valley Road, they came to the house of Joshua and Angie Wickander. The front of the house looked as though it had been hit by a meteor. Insulation dust covered everything inside.

"I should be dead, I should be broke, I should be beaten," said Joshua Wickander.

His wife, Angie, and one of their two sons were trapped for a few minutes after the storm passed. Neighbors clawed away debris to get them out the front door. Their other son was down the block when an alert neighbor grabbed him seconds before the storm hit and hurried him into her house. Joshua Wickander was in a vehicle nearby. A tree fell near him, he said.

The storm took their home but renewed their faith in friends and neighbors -- and in their insurance company. They got a check for their house on Tuesday.

The family plans to move closer to his job in Chisago City, but they're not happy to be leaving north Minneapolis.

"This is not an eyesore. This is a neighborhood," said Wickander. "These people," he said, pointing to his neighbor's houses, "when they saw my house, they didn't even care about their own -- they ran here to get my kids out."

Wickander said he plans to donate their lot to any non-profit agency that promises to build a single-family home on it.

The disaster center that has served more than 2,500 area residents at Farview Park will remain open through at least Tuesday, the city announced. Hours will be 9 a.m. to 7 p.m. Friday, 9 a.m. to 4 p.m. Saturday through Monday, and noon to 8 p.m. on Tuesday.